Conventionally, as the tire vulcanizing press of this type, there has been known such a press as shown in FIG. 22 and FIG. 23 (taken along the arrow D in FIG. 22).
In FIGS. 22 and 23, a main body frame 21 of this tire vulcanizing press includes an upper frame 21a, a lower frame 21b and two side frames 21c and 21d. A lower mold 23 is fixed on the lower frame 21b through a lower mold mounting member 22. An upper mold 24, which is intended to be surface-contacted with the lower mold 23 and to be freely opened/closed, is fixed on an upper mold mounting member 25. The end portions of piston rods 27 of two liftable cylinders 26 provided on side portions of the upper frame 21a are fixed on the upper mold mounting member 25. Guide members 28 are disposed between both side portions 25a and 25b of the upper mold mounting member 25 and both the side frames 21c and 21d, respectively. The guide members 28 include rails 29 mounted on the side frames 21c and 21d, and rollers 30 mounted on the side portions 25a and 25b of the upper mold mounting member 25. By traveling of the rollers 30 along the traveling surfaces 29a of the rails 29 which are mechanically finished with high accuracy, the upper mold mounting member 25 is vertically liftable with respect to the lower mold mounting member 22. Further, a pressure transmitting rod 31 is erected on the upper mold mounting member 25, and the upper portion of the pressure transmitting rod 31 is inserted in a hollow pressure cylinder 32 fixed on the upper frame 21a.
Next, the operation of the above tire vulcanizing pressure will be described.
The upper mold mounting member 25 is lifted by contracting the piston rod 27 of the liftable cylinder 26, to lift the upper mold 24. A green tire is thus set to be charged in the lower mold 23.
Then, the upper mold mounting member 25 is lowered by extending the piston rod 27 of the liftable cylinder 26, to lower the upper mold 24, thereby closing both the molds 23 and 24. Subsequently, the hollow pressure cylinder 32 is operated to transmit a pressure to the pressure transmitting rod 31, to perform the clamping operation.
After completion of the clamping operation, the piston rod 27 of the liftable cylinder 26 is contracted, to lift the upper mold mounting member 25. The tire thus vulcanized is discharged outside the apparatus by use of an unloader or the like. With this operation, the tire vulcanizing operation is completed, and a new green tire is set to be charged in the lower mold 23 by use of a loader or the like, to thus start the next vulcanizing operation.
In the tire vulcanizing press described in the prior art, the guide members 28 composed of the rollers 30 and the rails 29 are disposed at two points, that is, between both the side portions 25a and 25b of the upper mold mounting member 25 and both the side frames 21c and 21d, respectively.
As a result, it is required to adjust the parallelism between the guide members 28 disposed at two points; however, in the case of the tire vulcanizing press, this adjustment is difficult because of the thermal deformation due to the vulcanizing heat. Further, the upper mold mounting member 25 and the side frames 21c and 21d require large mounting areas for mounting the guide members 28. This causes a disadvantage in enlarging the areas to be machined, resulting in the increased cost.
Additionally, there is known such a tire vulcanizing press as disclosed in Unexamined Japanese Patent Publication SHO 58-71143.
In this tire vulcanizing press, a lower mold is fixed on the lower portion within a frame-like main body frame, and an upper mold is provided on the lower side of a liftable base (upper mold mounting member) liftably supported within the main body frame. On the other hand, a mold pressurizing apparatus is fixed on the upper portion of the main body frame, and a spacer which is intended to be interposed between the mold pressurizing apparatus and the liftable base at the lowering position is provided in such a manner as to be freely escaped sideward.
When the upper and lower molds are pressurized by the mold pressurizing apparatus, the spacer is interposed between the mold pressurizing apparatus and the liftable base. Besides, when the upper and lower molds are opened/closed, the liftable base is lifted/lowered while the spacer is escaped sideward.
Further, there is known the so-called twin type tire vulcanizing press, wherein two sets of vulcanizing mold apparatuses respectively provided with mold pressurizing apparatuses (clamping apparatuses) are juxtaposed in the lateral direction.
The prior art tire vulcanizing press requires a spacer having a length being nearly equivalent to the lifting/lowering stroke of the liftable base. This causes a disadvantage that the main body frame is made longer in the vertical direction, to thus enlarge the whole size of the vulcanizing apparatus.
Further, in the twin type tire vulcanizing press, during a molding cycle (15 min, at the present situation), the vulcanizing time (during clamping) is made longer, and the charging time of a green tire and the ejecting time of the tire (loading/unloading time) are made shorter. Consequently, it has been considered that the shearing of the clamping apparatus was unreasonable.
However, in the current tire vulcanizing press, the vulcanizing time has been made shorter, and in the future, the loading/unloading time may be made rather longer. In this case, the lowering of the operating efficiency of the clamping apparatus is at stake, and the cost-down is not expected.